1. Field of the Invention
The present invention relates to the field of computer networking and, in particular, to the field of Asynchronous Transfer Mode (ATM) communications. In its preferred embodiment, the present invention is used to provide high speed interfaces for interconnection between switches and for connection to servers in a network communications system while allowing an existing installed base of wiring and adapter cards to stay in place by combining an ATM switched network with switched Ethernet (or other shared media communication system) as the connectivity to general class desktop computers.
2. Description of the Related Art
Asynchronous Transfer Mode (ATM) technology is a relatively new approach for providing communications services between devices in a computer network or the like. This technology provides the benefits of circuit switching (e.g., for voice and video applications) and the benefits of packet switching (e.g., for computer communications.) ATM technology is characterized by its use of groups or "cells", as they are typically called in the art, of a fixed size and format.
Typically, an ATM network is implemented using a network of interconnected switches. Each switch supports a number of ports and provides dedicated bandwidth on each port. This is in contrast to typical existing shared local area networks (LANs) where the bandwidth is shared by all users on a LAN segment. It is hoped that commercial implementations of ATM networks will provide port interface speeds of 155 Mbps and higher. In LAN environments, such high speed networks may be used for interconnecting high performance computers such as servers, mainframes, and high performance desktop computers.
It is thought that, in time, ATM networks will be used by more general class desktop machines, such as for delivery of multimedia services. However, in the short term, the extra bandwidth and cost of ATM interfaces is probably not justified for general class desktop machines. However, existing shared media LANs are, at least, beginning to become a bottleneck in computing environments. The continual improvement in the compute power of general class desktop computers, as well as the development of new applications such as multimedia, will cause shared media LANs to become increasingly a bottleneck in computer networks in the future.
There are a number of approaches which have been suggested to relieve such bottlenecks:
(1) Segment the shared media LANs - This approach calls for increasing the number of LAN segments in a network with fewer users per segment. The segments are interconnected using bridging or routing. Of course, using this approach, the bandwidth is still shared although it is shared among fewer users; PA1 (2) Segment the shared media LANs (extreme case) - It is, of course, possible to take the segmenting approach to an extreme and provide one segment per device. In this case, each port is effectively bridged. Of course, while this approach effectively gives dedicated bandwidth to the device, it has drawbacks both in terms of cost and network size (network size is limited because all interfaces are the same speed); PA1 (3) Build ATM switches with lower speed ATM interfaces - This is a technically attractive approach; however, it presents a serious deployment problem in that it requires replacement of the substantial installed base of shared media LAN wiring and adapter cards. PA1 1) Terminals - Refers generally to the devices that terminate a network connection. These can be computers, printers, null devices and virtually any other device that communicates with other devices. PA1 2) Ports - Refers generally to a logical and/or physical access point to the network. PA1 3) Concentrator- Refers generally to communications devices for receiving information on multiple ports and transmitting the information on one or more of the ports. Concentrators are generally well-known in the art. The present invention discloses a specialized concentrator for receiving information on Ethernet ports and transmitting the information onto an output port coupled with an ATM network. The concentrator provides for segmentation of Ethernet packets into ATM cells prior to transmission onto the ATM network. Conversely, the device of the present invention can receive information on ATM ports and output the information on Ethernet ports. The concentrator also provides for reassembly of Ethernet packets from received ATM cells prior to output of the information onto the Ethernet ports. It might also be noted that the present invention provides for allowing communication between the various Ethernet ports.
Thus, what is desired is to develop a network providing increased bandwidth, and preferably dedicated bandwidth, with minimal cost, maximum support of large network sizes, and minimal displacement of existing installed equipment.
Having stated all of the above, it may now be worthwhile to briefly provide some further background information on (1) ATM networks, (2) Ethernet networks and (3) terminology.